The present invention relates to a facsimile set and more particularly a facsimile set capable of the automatic transmission and reception through the conventional telephone channel.
There has been devised and demonstrated a facsimile system in which unattended facsimile sets at remote stations are intercommunicated through the conventional telephone channel for automatic transmission and reception. A calling subscriber's facsimile set is automatically actuated at a predetermined time to connect it to the telephone line (or switch lit into the off-hook mode) and then transmit the digit pulses for calling a desired subscriber's facsimile set. In response to the ringing signal, the called subscriber's facsimile set is automatically actuated to establish the DC telephone circuit or loop with the calling facsimile set. The facsimile system of the type described is similar in operation to a telephone answering system which answers the incoming calls with a prerecorded message when a subscriber is absent and permits the caller to record a message in turn. When the called facsimile set is actuated, it accomplishes a routine check to see if it is in the conditions capable of receiving and reproducing the image transmitted. If the called facsimile set is ready for reception, it answers back so that the calling facsimile set starts the transmission of the image. The called facsimile set reproduces the image transmitted, and after the reproduction of all the images transmitted, it is reset to the initial state and is disconnected from the telephone circuit with the calling subscriber. In like manner, after the transmission of all the images required, the calling facsimile set resets to the initial state and is automatically disconnected from the telephone circuit with the called facsimile set, that is, it is switched to the on-hook mode.
In the facsimile system of the type described, both the calling and called facsimile sets are reset to the initial state after the transmission and reception have been accomplished under the normal conditions. Therefore they are ready to receive a call from any other subscribers. However the normal transmission and reception are often disturbed by various reasons. For instance, (1) when the power supply is cut off, (2) when too many errors are found in transmitted data, (3) when erratic operations are caused by an operator or (4) when erratic operation of a telephone switching system occurs, both the calling and called facsimile sets must be immediately hung up or switched into the "on-hook" mode to be disconnected from the telephone circuit.
However, when the master and the recording sheet still remain at the reading and recording positions, respectively, this means that both the calling and called facsimile sets are still busy. As a result, even when they are called again, they cannot answer so that the intercommunication between these facsimile sets cannot be established any longer. Therefore there can be no re-transmission, and the signal representing the disabled facsimile set cannot be received. It is of course undesirable for the facsimile sets to remain in such disabled conditions for a long time.
One of the objects of the present invention is to provide a facsimile system in which when the hangup of a calling or called facsimile set occurs, the master or recording sheet may be immediately removed out of the reading or recording position and the facsimile reader or recorder may be immediately reset so that the intercommunication between the calling and called facsimile sets may be recovered within a short time.
Another object of the present invention is to provide a facsimile set in which when the hangup occurs during the transmission or reception, alarm or warning means gives the alarm or warning signals to the operator so that he may immediately start again the transmission or reception from the beginning.
To attain the above and other objects, a facsimile set in accordance with the present invention includes means for detecting its own hangup and/or hangup of the other subscriber's facsimile set, and means for detecting whether or not the master or recording sheet remains in the reading or recording position when the hangup occurs. In response to the outputs of the above two means, the facsimile set is automatically disconnected from the telephone circuit, and the master or recording sheet is immediately discharged out of the reading or recording position so that the facsimile reader or recorder may be reset for re-transmission or re-reception from the beginning. Moreover alarm or warning means is provided to give alarm or warning signals to the operator.
The present invention will become more apparent from the following description of the preferred embodiments thereof taken in conjunction with the accompanying drawing.